This paper presents a dynamic model of a quadrotor UAV affected by a blast wave that impinges on the vehicle. The body of a quadrotor is decomposed into four spherical motor elements connected by rods to a central spherical body. Existing models for the pressure and induced air velocity of a blast wave are adapted for this work and compared to computational fluid dynamics (CFD) simulations. The response of a single sphere to a blast wave is characterized by integrating the pressure over the sphere to obtain an impulse due to the pressure wave and drag. This analysis is extended to the multi-sphere model of the quadrotor UAV. As the blast interacts with the UAV, the non-uniform pressure over the body results in forces and moments that perturb the vehicle. Similarly, the blast-induced wind generates drag forces that are superimposed. The response of the vehicle to the blast pressure and wind is investigated by numerically integrating the equations of motion over the short duration of the blast to determine the terminal state of the UAV after 100 ms when the surroundings return to ambient conditions.

This paper presents a data-set of performance characteristics of nearly two hundred vertical/short takeoff and landing (V/STOL) uncrewed aerial systems (UAS). Characteristics of the UAS that are recorded include maximum gross takeoff weight, endurance, maximum length dimension, speed, payload, and payload fraction. The data-set is restricted to small UAS that weigh under 500 lbs. The results are visualized via scatter plots and statistically characterized. The performance of different UAS design types and UAS Group Numbers are compared. The data-set provides a snapshot of current capabilities of small UAS in the V/STOL category and may be useful to UAS developers and procurement agencies.

This paper presents a framework for training a Gaussian process (GP) to estimate a steady urban wind field from a sparse set of wind measurements by leveraging training data collected from computational fluid dynamics (CFD) simulations. Gaussian process models for spatial estimation often use measurement locations as the input space with proximity-based covariance functions. This work investigates including building morphology features into the GP model that are defined by the signed distance field (SDF) and its gradient evaluated at a pattern of points around each sample location. Augmenting the measurement locations with different subsets of building morphology features leads to unique feature spaces. Several different GP models are trained using various feature spaces and covariance functions, including with a coregion covariance function that allows simultaneous training over multiple CFD datasets for different urban geometries. A framework is developed to generate CFD wind field data for a set of randomized geometries, build various feature spaces, and perform the estimation with the proposed GP models. The framework is evaluated with a simple environment that consists of two buildings with randomized position and geometry in a wind field with constant inflow magnitude and direction. Results are presented comparing the estimation performance across different GP models with an increasing number of optimization iterations. The computation versus accuracy trade-off of using hyperparameters trained over multiple similar prior CFD datasets, rather than hyperparameters that are optimized on-the-fly, over a single dataset is also demonstrated.

This paper presents a software pipeline that enables simulating a quadrotor’s flight in realistic urban wind fields where complex wind phenomena are common and have significant impact on vehicle dynamics. The pipeline integrates the OpenStreetMap database for obtaining real-world building geometry, the OpenFOAM computational fluid dynamics (CFD) solver for computing a three-dimensional, steady, wind field, the Gazebo robotics simulation environment, and the PX4 software-in-the-loop autopilot. A 3D wind plugin is developed to interpolate a pre-computed CFD wind field at runtime during the simulation. The approach is demonstrated by comparing the flight performance of a quadrotor flying over a university campus environment with and without the wind field.